The present invention relates to an apparatus and method for automatic stripping and removal of a protective film from a planar substrate and particularly from a polymer sheet such as plexiglass and the like.
Polymeric sheets, for example, have historically been utilized in fabrication of various and sundry structures. Typically, such sheets are provided to a fabricator as planar sheets of a certain size which must be cut to a predetermined size and shape as needed for a particular fabrication process. Exemplary of polymer sheets of the type being discussed herein are polymethylmethacrylate sheets which are sometimes referred to as plexiglass. During fabrication, the sheets may be cut, milled, shaped, drilled and otherwise manipulated to facilitate fabrication of an intended structure. After working the sheet(s), to the desired size and shape, these sheets are used in fabrication of the intended article. Just by way of example, and without limitation, many display supports of various and sundry sizes and shapes are fabricated from such polymeric sheets. Often in use of the structures fabricated from the polymeric sheets, smooth transparent surfaces add to the aesthetic or functional qualities of the structure.
Typically, the planar sheets of the polymeric materials have an optical quality of transparency. However, due to softness of the surfaces of the sheets, the sheets are easily scratched or otherwise deformed, detracting from the conventional optical qualities of the sheets, and ultimately therefor the aesthetics of the structures fabricated therefrom. Consequently, in order to protect the polymeric sheets against scratching and the like, a protective flexible film or cover is routinely secured along opposite sides of the sheet and normally remains in place until the sheet is used in fabrication of the intended structure, or even in some cases after the structure is produced and until the product is ready for its intended use.
In the past, though some machines have been developed to remove protective covers, there has been a general industry practice of manual removal of the protective covers from the sheets at the appropriate time. Manual removal of the protective covers from the polymeric sheets, as would be expected, is labor intensive, and therefore not desirable.
Similarly, in the electronics field, printed circuits, in some instances, have a protective film cover provided across one or both sides of the circuit being produced which must be stripped during or prior to the process for manufacture of the printed circuit board. Particularly in a process where a portion of the board is photographically processed to achieve a particular functional element of the circuit, protective covers are employed. In this industry, machines also have been previously developed for automatically removing the protective film cover from the printed circuit boards.
Exemplary of prior art efforts directed to removal of protective covers from planar substrates are U.S. Pat. Nos. 2,337,724; 4,274,676; 4,724,032; 4,770,733; 4,867,836; 5,358,591; and 5,662,762.
The present invention represents an improvement over the apparatus and processes described in the above prior art patents. Particularly, it is submitted that the present invention is patentable over the above listed prior art patents taken either alone or in combination.
It is an object of the present invention to provide apparatus for the automatic removal of protective cover from polymeric or other sheets.
Another object of the present invention is to provide an improved apparatus for the automatic removal of a protective layer from a substrate.
Still another object of the present invention is to provide an improved apparatus for the automatic removal of an outer film layer from a planar polymeric substrate.
Still further another object of the present invention is to provide an improved method for the automatic removal of a protective film from a substrate.
Yet another object of the present invention is to provide an improved method for the removal of a flexible film layer from one or both sides of a polymeric sheet.
Generally speaking, apparatus according to the present invention comprises a conveyor arrangement for engaging and moving a sheet having a protective cover on one or both sides of same along a predetermined path; an air nozzle system located along a continuation of said path for said sheet and being disposed at a predetermined angular relationship with respect to a sheet passing along said path for directing gas under pressure against said protective cover adequate to partially dislodge said cover from said side of said sheet; a driven roll located proximate said air nozzle system and said path, said roll having a capability for receiving and holding a portion of protective cover dislodged from said surface for further removal of same as said sheet passes thereby; and a suction system located adjacent said roll for receiving said protective cover from said roll and transporting said protective cover away.
More specifically, apparatus according to a preferred embodiment of the present invention includes a pair of opposed driven belts that define a passageway therebetween, preferably adjustable, for a planar sheet and cooperate with the planar sheet therebetween to move same along said passageway which is an intended path of travel. A plurality of air jets are angularly disposed with respect to a continuation of the path followed by the sheet for directing air under pressure against the cover to initially and partially dislodge the cover so that the cover can be completely removed from said sheet. A suction duct is located along the path, adjacent the air nozzles with a driven roll in close proximity to the air nozzles for receiving a portion of the cover as it is dislodged from the sheet and transporting the dislodged portion of the cover and presenting same to the effects of suction in the suction duct so that when the cover is fully dislodged from the sheet the cover is carried away by the force of suction in the duct. A second conveyor may be provided for movement of the sheet away from the air jets.
Generally speaking, the method according to the present invention for removing a protective cover from a planar substrate comprises the steps of transporting a sheet with a protective cover thereon along an intended path of travel; directing air under pressure at a predetermined angle to said path against said cover to dislodge a portion of said cover from said sheet; engaging a portion of said cover dislodged from said sheet with a driven roll and continuing gradual removal of said cover; presenting said portion of said cover to the effects of a source of suction adequate to hold said portion and transport said cover away after said cover is completely removed from said sheet.
More specifically, according to a preferred embodiment of the present invention, a planar substrate having a protective film cover on opposite sides of same is fed under controlled conditions to a stripping station where air under pressure is directed at a predetermined angle with respect to the interface between the substrate and the protective cover and partially dislodges the film from the sheet. The partially dislodged film is forced by the air against a driven roll located closely proximate the nozzles and the sheet. The driven roll grabs and holds the cover and as the roll rotates continues to remove the cover from the sheet and present the cover to the effects of a source of suction. The removed cover is then transported away by the suction and the sheet, now stripped, is conveyed away from the stripping area.